Cyclone bad news (and maybe some good news) for reef

The Great Barrier Reef has had a tough 12 months.

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Last year brought record-high ocean temperatures, followed by major bleaching events, and, now, Cyclone Debbie has caused even more destruction of the reef.

Cyclonic winds churn the sea and can cause damage to the delicate ecosystem.

Great Barrier Reef Marine Park Authority spokesman Mark Read says the reef’s outlook right now is grim.

“We had a very, very large system, an incredibly big system. Unusually, Debbie spent quite a long time crossing the Great Barrier Reef as well, where some of the other cyclones … such as Tropical Cyclone Yasi was very quick as it traversed the reef. And when we put all those things together, the prediction is that the damage is likely to be widespread and, potentially, quite severe.”

The effects of climate change mean the world will see more extreme-weather events such as cyclones.

James Cook University geoscience professor Jonathan Nott is a specialist in extreme-weather events.

Professor Nott says a changing climate means the number of cyclones battering Queensland’s coast is expected to decrease but the cyclones that do arrive will be more severe.

“The global climate models are forecasting that we will see a decrease in the total number of cyclones that we experience in the Coral Sea regions, so off the east coast of Queensland. But those cyclones we do experience are expected to increase in magnitude. And our research has shown that it appears that we’re already starting to experience a decrease. We’re not so sure about an increase in magnitude, but some studies have been done to suggest that magnitudes are increasing in tropical cyclones throughout the south-west Pacific.”

The Great Barrier Reef is one of Australia’s most valuable natural assets, and damage to the reef is likely to impact tourism and the Queensland economy.

Queensland Tourism Industry Council chief executive Daniel Gschwind says the council is concerned about the reef’s health.

“Of course, the reporting and the reality that the reef is under threat is something that we are very concerned about. And the tourism industry is working very hard to do its bit to make the reef resilient, to help the reef withstand the threats, whether they are natural or otherwise.”

Last year, some of the warmest ocean temperatures on record in Australia contributed to several mass-bleaching events across the reef.

But Mr Read says there is a positive side to the cyclone, too, because those types of storms typically cool down ocean temperatures.

“Tropical cyclones can cool down the Great Barrier Reef, or the waters of the Great Barrier Reef — number one, by the cloud cover, number two, by the rainfall associated with a cyclone and, number three, because of the winds that can actually ruffle the sea surface, which improves … or reduces the ability of the water to heat up. But, also, you can have massive deep-water movements caused by the cyclones as well. All of those things can contribute to cooling the water by a couple of degrees.”

Mr Read says people also need to be reminded the reef has been around a long time and cyclones are nothing new.

“Absolutely, the reef can bounce back from a tropical cyclone. You know, we just always need to bear in mind that the reef has been there as we know it today for in the vicinity of 6,000 to 8,000 years. And tropical cyclones are nothing new. This is a natural feature that the reef had come to deal with.”

Previous studies of reef repair after cyclones show they usually recover within three to five years.